Lamp holders are commonly used in applications in which they are subject to vibrations or impacts, such as in motor vehicles, airplanes, or industrial areas subject to vibrations from heavy machinery. For these applications, it is desirable to provide a lamp holder that is resistant to vibrations or impacts.
Frequently, lamp holders are also used in corrosive applications, such as in marine environments. It is desirable in these applications to provide a lamp holder that is highly resistant to the effects of marine or other corrosive environments.
Conventional lamp holders typically include an insulating shell of plastic or ceramic and a socket adapted to accept a lamp. The plastic and ceramic sockets are typically rigid materials that are very adept at transferring vibrations and shocks to the attached lamp. When subjected to continued vibration or sudden or repeated shocks, the lamps are prone to loosening from the lamp holder. This is a problem common to most lamp holders and their complementary lamps, and may include screw-type sockets, bayonet-type bulbs and holders, lamps having prongs, or simple push-in type lamps and their associated holders. All of these common lamp holders are subject to failure under conditions of vibration or shock.
Although several attempts have been made to provide lamps that are resistant to vibrations and impacts, the lamp holder remains subject to failure from shock and vibration. For example, Sutter, in U.S. Pat. No. 4,112,485, has disclosed a lamp comprising one or more light sources encapsulated in a relatively soft impact absorbing transparent material, which is in turn encapsulated in a relatively hard impact resistant material, such as acrylic or glass.
Sica, U.S. Pat. No. 5,536,998 is directed to a protective assembly for a standard fluorescent lamp. The assembly includes a protective tube preformed from a semi-rigid, transparent material that is received over a glass tube. The inner surface of the protective tube is uniformly spaced apart from the outer surface of the glass tube to form an air space for insulation of the lamp. The desired uniform spacing between the lamp tube and the protective tube is established by a spacer ring located adjacent each end of the glass tube and adhesively bonded to the glass tube. Each spacer ring is formed of a band of semi-rigid polymeric foam strip material. The protective tube and air gap provide protection to the glass tube with the protective tube absorbing impacts and minimizing the possibility of the lamp being broken.
Bedford, et al, U.S. Pat. No. 5,676,459 discloses a door-mounted vibration-tolerant lamp assembly comprising a door-mounting brace for mounting the lamp assembly to an exterior surface of a door. The lamp assembly includes an elastic mount having a mounting bracket and at least one resilient pad disposed between the mounting bracket of the elastic mount and a mounting bracket attached to the door mounting brace such that the resilient pad absorbs a substantial amount of the vibration that is generated when the door is moved to a closed position.
Although various devices are described in the prior art for minimizing the effects of vibration and shock to electric lamps, they do not address the effects of vibration and shock upon the lamp holders. Additionally, enclosing the lamps within multiple tubes increases the cost of the lamps and necessitates the use of a specialized lamp in environments subject to vibration or shock.
Furthermore, the prior art does not address the problems presented by the use of metal conductors in a corrosive environment, which can cause fusion or “locking up” of separate metal components that are in contact with one another.
What is needed therefore is an impact resistant, vibration resistant, and corrosion resistant lamp holder that is capable of protecting a common light bulb. The lamp holder should be capable of protecting various common light sources, such as incandescent, fluorescent, or halogen bulbs. The lamp holder should also be capable of accommodating various bulb connection arrangements, such as screw-in, bayonet, prongs, or push-in type arrangements.